The present proposal seeks to address how multiple structures interact to mediate active navigation. The ability to learn and remember locations of important resources is absolutely critical for every animal's ability to survive. As such, it is of great importance to understand how neural systems interact to mediate this behavior. The proposed studies will evaluate cortical contributions to processing of spatial information in hippocampus and limbic thalamus. Past anatomical, lesion and electrophysiological data suggest the retrosplenial cortex may make unique contributions to spatial learning. It is hypothesized here that retrosplenial cortex importantly contributes to the integration of visual and self movement information in limbic structures thought to be involved in navigation. To test this hypothesis, permanent lesions and temporary inactivation of retrosplenial cortex will be combined with chronic single unit recording from hippocampus and thalamus during active navigation. Behavioral probe trials will be used to identify changes in behavioral strategies following removal of retrosplenial cortex. It is predicted that in the absence of retrosplenial cortex the integration of visual and self movement information will be diminished in spatial correlates recorded from thalamus and hippocampus and behavioral data will reflect similar changes in behavioral strategies underlying spatial memory performance.